Thermal imaging cameras are used in a variety of situations. For example, thermal imaging cameras are often used during maintenance inspections to thermally inspect equipment. Example equipment may include rotating machinery, electrical panels, or rows of circuit breakers, among other types of equipment. Thermal inspections can use infrared (IR) energy detection to detect equipment hot spots such as overheating machinery or electrical components, helping to ensure timely repair or replacement of the overheating equipment before a more significant problem develops.
Depending on the configuration of the camera, the thermal imaging camera may also generate a visible light image of the same object. The camera may display the infrared image and the visible light image in a coordinated manner, for example, to help an operator interpret the thermal image generated by the thermal imaging camera. Unlike visible light images which generally provide good contrast between different objects, it is often difficult to recognize and distinguish different features in a thermal image as compared to the real-world scene. For this reason, an operator may rely on a visible light image to help interpret and focus the thermal image.
In some embodiments, an add-on lens is used with the thermal imaging camera to adjust the field of view acquired infrared or visible light images. Add-on lenses can be attached in a variety of ways, such as via a bayonet mounting mechanism. When a bayonet mechanism is used to attach an add-on lens assembly that is used to change the focal length of a lens system, alignment is very important, either to maintain performance and/or boresight requirements. Typical bayonets used on an infrared camera are limited in how large the lens can be. This is because the bayonet mechanism has a spring that provides an axial force to assure the add-on lens is aligned with the base unit. If the spring force is too high, it becomes difficult to attach the lens. Therefore, it is a compromise between how large a lens can be, and how difficult it is to attach a lens. Typical solutions for larger lenses are to provide an external support, which has to be carried separately and installed when it is time to use the lens. This invention eliminates the need for this support, by increasing the axial force on the bayonet with a cam operated mechanism.